Railway signaling system



Mmh A16, 1937. G. CAME y 2,074,163

RAILWAY SIGNALING SYSTEM Filed March 28, 19:54 s sheets-'sheet 1 C f/g/*f e7 V 2\ L K Illa/m m *s e B A X F"i 2x 'o lg.' C5 5l 52 53 R www EDR;s Uil 3 .X lz ..1 x X Bl /5 FR, B i -:Ifj B* H23 f f klo' /5 Mo l //1 8XX J [4J-J6 B l [M55/ix 2LP/4 if C Figs.

Ck X 2o l8- FR I 23 TR A /9 'l um 'lg/r I 16, 1937. Q CAILLE 2,074,163

RAILWAY SIGNALING SYSTEM Filed March 28, 1954 3 Sheets-Sheet 2 INVE/Vml?Geo/gaf Caille B22/RM Hi.;q ATTORNEY ch E6, E37 G. CAILLE ZWMB i RAILWAYSIGNALING SYSTEM Filed March 28, 1954 s sheets-shea s INI/N701? GpofgewCai Il@ BY His ATTog/vEr/ Patented Mar. 16, 1937 Nunirse RAliLWAYSIGNALING SYSTEM of Pennsylvania Application March 28,

1934, Serial No. V'717,821

In France April l2, 1933 15 Claims.

This `invention relates, to railway signaling systems of the kind inwhich track circuits constituted bythe track rails divided into blocksections are utilized for the automatic control of the signals of thesystem in accordance with the presence or absence of a train or vehiclein or from a block section.

In signaling systems of the character above indicated the track circuitsare usually arranged to be continuously supplied with signaling cur--rent with a correspondingly continuous expenditure of electrical energyand the invention has for its vprincipal object to provide a signalingsystem of lthe track circuit type in which signaling current is arrangedto be supplied to the track circuit of a .block section only upon theapproach of a train or vehicle, the track circuit -being deenergizedexcept under these conditions.

In existing signaling systems comprising continuously energized trackcircuits the presence of a train or vehicle in a block section isarranged to be detected for the purpose of controlling signalindications by means of a track relay connected across the track railsof the section so as to be deenergized by the wheels and axles of atrain or vehicle entering the section, but it will be evident that thisarrangement cannot be Vadopted'in a signaling system in which the trackcircuits are not continuously energized since the track relay Will bedeenergized under normal conditions Whether the section is or is 'notoccupied by a train or Vehicle.

A further object of the invention is accordingly to provide arrangementsfor detecting the `:lnesence of a train or vehicle in a block sectionunderall conditions of operation whenever such detection is required, astill further object of the invention being to provide a signalingsystem comprising track circuits which are not continuously energized,in which the failure of the supply of electric current to any portion ofthe system will cause a danger signal to be given and'thus ensurecomplete safety in operation.

The invention is illustrated by way of example in the accompanyingdrawings of which Figure 1 is a diagrammatic View of the circuitconnections of a portion of a track circuit signaling systemillustrating the principle of the invention.

Figure 2 is a diagrammatic View ci a number of successive block sectionsof a railway track provided with a signaling system embodying one formof the invention.

Fig. 2EL is a diagrammatic view, similar to Fig. l, showing the controlcircuit for the disagree- .0.55 ment relays of Fig. 2-

Figure 3 is a diagrammatic view similar to `a portion4 of Figure l'illustrating certain c1rcu1t connections,

tion.

Figures 5 and 6 are diagrammatic views illustrating two dilferentembodiments of the invention as applied to the control of the signalsfor a number of successive block sections of-aV railway track. 1 i

Referring now first to Figure 1, it will be seen that the track rails ofa block section 'C are indicated at l, 2 as isolated from the trackrails of the preceding and succeeding block sections by the usualinsulated joints 3. The block section C is provided with a track relayTR connected across the track rails l, 2 in the usual manner and is alsoprovided with a track feed relay FR adapted to be controlled in anysuitable manner by the approach of a train or vehicle towards the blocksection C.

The feed relay FR is provided with relay contacts adapted to control thesupply of signaling current to the track rails l, 2 in such a mannerlthat this supply is effected when a train or vehicle approaches theblock section, the feed relay being thereby caused to occupy what may betermed its feed position, while under all other conditions the feedrelay is caused to occupy its non-feed position.

The track relay TR is in its energized position when signaling currentis supplied to the track rails I, 2 and the block section is unoccupiedby a train or vehicle, this relay'assuming its deenergized position whenthe block section is occupied or when signaling current is not beingsupplied to the track rails.

As already explained the presence of a train or vehicle in the blocksection cannot under all conditions be detected by the deenergization ofthe relay TR and in accordance with the principle of the invention thepositions of the feed and track relays FR and TR relative to each otheras distinct from the actual positions of either of these relays isarranged to indicate whether the block section is occupied orunoccupied.

When the track relay TR is in its energized position and the feed relayFR is in its feed position, the two relays may be said to be inagreement with each other as is the case also when the track relay TR isin its deenergized position and the feed relay FR is in its non-feedposition.

When, however, the track relay TR is in its deenergized position withthe feed relay FR in its`A Figure 4 being a similar view of a modicaufeed position or if the track relay TR should be in its energizedposition with the feed relay FR in its non-feed position the two relaysmay be Said to be in disagreement with each other.

The feed position of the feed relay FR may be arranged to correspondeither to the energized (Fig. 2a arrangement) or deenergized (Fig. 1arrangement) of this relay and it will be evident that the relays TR andFR in either Fig. 2a or Fig. 1 will be in agreement with each other onlywhen a train or vehicle approaches the block section and this section isunoccupied.

In the simple system illustrated diagrammatically in Figure 1 the relayFR is arranged to assume its feed position when deenergized, this relaybeing normally energized and being deenergized by means not shown when atrain or vehicle approaches the block section C in the directionindicated by the arrow. The system of Fig. 1 saves power in that thetrack circuits are normally deenergized, but some power is, of course,expended in maintaining the feed relays FR normally energized.

` 'I'he signal S at the entrance to the block section is shown asarranged to be controlled by an electrically operated device DR of anysuitable type and it will be seen that under normal conditions the relayFR being energized and in its non-feed position, so that the relay TR isdeenergized, a circuit is completed from a terminal B of a source ofelectric current through the device DR, back contact 4 of relay TR, wire5, front contact 6 of relay FR to the other terminal X of the source ofcurrent.

The device DR is thus energized and operates the signal S to give aproceed indication.

In the event of failure of current supply to the relay FR the circuitfor the device DR will be broken at the contact E so that the device DRwill be deenergized and will operate the signal S to give a stopindication.

A similar action will evidently take place in the event of failure ofthe current supply to the ldevice DR or in the event of current from anextraneous source being supplied to the track rails I, 2 so as toenergize the relay TR and interrupt the circuit of the device DR at thecontact 4.

When a train or vehicle approaches the block section the relay FR isdeenergized and assumes its feed position in which current is suppliedto the track rails I, 2 from terminal B, back Contact 'I of relay FR,wire 8, rails I and 2, wire 9, back contact I of relay FR to terminal X.

Assuming that the block section C is unoccupied the relay TR will becomeenergized and a circuit will be completed from terminal B, device DR,front contact 4 of relay TR, wire I I, back contact 6 of relay FR toterminal X.

The device DR under these conditions will still be energized so as tocause the signal S to give a proceed indication.

Under these conditions it will be seen that the proceed signalindication is due to the relays TR and FR being in agreement with eachother.

If, however, the block section C is occupied when the train approaches,the relay TR will be deenergized although the relay FR is in its feedposition, so that the relays TR and FR will be in disagreement with eachother and the circuit of the device DR will be broken at the frontcontact 4 of the relay TR thereby causing a stop signal indication to begiven at the signal S.

Assuming that the block section C is unoccupied and the trainconsequently enters the block section, the relay FR is arranged toremain .deenergized and the relay TR being deenergized by the presenceof the train, the relays TR and FR will consequently be in disagreementwith each other so that a stop signal indication will continue to begiven at the signal S so long as the train remains in the block section.The deenergization of relay FR during occupancy of section C will beclear from the description of Fig. 5, in which a similar operation takesplace.

When the train passes out of the block section the relay FR isreenergized and assumes its nonfeed position so that the relay TR isdeenergized and the two relays being thus again in agreement with eachother, a proceed signal indication is given at the signal S.

Referring now to Figure 2, three successive block sections CI, C2, C3 ofa section of railway track are shown therein and are provided withcorresponding signals SI, S2, S3. The feed relays FRI, FR2, FR3 for thesections CI, C2, C3 respectively are in this case arranged to assumetheir feed positions when energized. Each block section is provided withdetector relays DRI, DR2, DR3 which are arranged to be controlled sothat each detector relay is energized when the corresponding track andfeed relays of the section are in agreement with each other, that is,are either both energized or both deenergized, as indicated by thecircuits for relay DR in Fig. 2l,

(the detector relay being deenergized when the track and feed relays arein disagreement.) Referring for the moment to Fig. 2a, it will be seenthat the circuit of this figure differs from the circuit of Fig. 1 inthat not only the track relays TR, but also the feed relays FR arenormally deenergized, thus effecting a maximum saving in power. Incontrast to the manner in which relay DR of Fig. 1 is controlled, theenergization of relay DR in Fig. 2a requires that relays TR and FR beboth energized, or both deenergized, in order that the condition ofagreement be established.

Referring again to Fig. 2, the track relays 'I'R for the track sectionsof this figure are not shown, for simplicity, but it will be understoodthat the control circuits for the relays DR in Fig. 2 are arranged asshown in Fig. 2a. Each of the feed relays is arranged to control thesupply of signaling current to the track rails of the correspondingblock section through relay contacts 'I, I8 as shown in the case of theblock section C2 and each block section is provided with a track relay(not shown) connected across the track rails in the usual manner asshown in Figure 2a.

Assuming that the block sections C2 and C3 are unoccupied and that atrain is present in the lock section CI, the detector relay DRI will bedeenergized since the track and feed relays of the section CI are indisagreement, the feed relay FRE being energized through a circuit fromterminal B, back contact I2 of relay DRI, wire I3, relay FRI to terminalX. 'I'he relay DRI also completes through a back contact I4 a circuitcausing a stop signal indication to be given at the signal SI.

A circuit is also completed under these conditions from terminal Bthrough back contact I5 of relay DRI, wires I6, I1, relay FR2 toterminal X, so that the relay FR2 is in its feed position and effectsthe supply of signaling current to the track rails of block section C2.Since this block section is unoccupied the detector relay DR2 isenergized owing to the track and feed relays of this section being inagreement and a circuit is completed at the front contact I4 of relayDR2 ."to cause the signal S2 to give a-proceed indication.,

The track and feed relays of block section C3 `being also in agreementthe detector Vrelay DR3is energized `and a proceed signal is thus alsogiven at the signal S3.

In theevent of the section C2 being already occupied it will beunderstood that the `track and "feed relays of this section will be indisagreement so that the detector relay DR2 will be deenergized xand acircuit will be completed at'the back contact I4 of this relay to causethe signal S2 to give a stop indication.

Assuming, however, that the section C2 is unoccupied and that the trainproceeds to pass'out `of section CI and to enter section C2, thedetector relay DRI will become energized as soon as the train has leftsection CI and will thus interrupt the circuit of relay FRI .at thecontact I2 and the circuit of relay FR2 at the contact I5.

While the train is passing from section CI `tosection C2, however, thedetector relay DR2 will become deenergized Vowing tothe deenergizationof the track relay of this section and the relay `FRZiwill continue tobe energized through a `circuit fromterminal'B, back contact I2 of relay`FR2, wire Il, relay DRZ to the terminal X.

The deenergization of the relay DR2 will cornplete at the back contactI4 of this relay a circuit causing the signal S2 to give a stopindication and at the back contact I5 of relay DR2 a circuit lelfectingthe energization of the feed relayFR3 of the section C3.

It will thus be seen that as the train proceeds the feed relay of eachblock section is energized `asthe train enters the preceding blocksection `and is maintained energized until the train has `completelypassed outof the block section.

` `At a terminus the feed relay of the rst block section is arrangedto'be'caused to assume its feed position by the train Vpassing over apedal switch -iorV by any other suitable device.

Referring now to Figure 3, the arrangement just described is utilized inthe case of each block section, a normally closed pedal switch P being4provided at a suitable position in advance of the l entrance to theblock section C.

The feed relay FR for the section is normally energized through aholding circuit from terminal B through switch P, wire I8, front contactI9 of relay FR, wire and relay FR to terminal X. The relay FR as. in thesystem of Figure 1 is, when energized, in its non-feed position so thatsignaling current is not supplied to the track rails of the section C.

The track relay TR is thus deenergized but as the train passes over thepedal switch P, the circuit of the feed relay FR is broken and the relayFR assumes its deenergized and feed position.

`gIn the event of the block section C being unoccupied the trackrelay'TRis thereupon energized and the track and feed relays of thissection being in agreement, the signal S is caused to give a proceedindication. r

As the train passes off the pedal switch P, this switch is reclosed butthe entrance of the train into the block section C causes thedeenergization of the relay FR to continue owing to its circuit beingbroken at the relay contact 2l, the original energizing or holdingcircuit of the relay FR having been broken at the relay contact I9 whenthe relay was first deenergized by the action of the pedal switch P.

The feed relay FR thus continues to be deenergized and to occupyits feedposition until the train has passed completely through and out o1 theblock section C whereupon the track relay TR `is reenergized and closesits contact 2| so that the relayY FR is energized over a pick-up circuitthrough wires I8 and 22, front contact 2|, andr wires 23 and 2U. Themovement of the relay FR kto its energized and non-feed position causesthe `relay TR to be deenergized and to open its contact 2| `but therelay FR is maintained energized `through its holding or stick contactI9.

The system of Figure 4` is similar to that of Figure 3 except that thepedal switch P of Figure 3 is replaced by the Contact 24 of a relay PRZwhich is connected across the track rails of the block section CI inadvanceof the section C2. It will be understood that when a train ispresent in this section CI the relay PR2 is deenergized and interruptsthe energizing circuit of the relay FR2 at the contact 24 of relay PR2.In other respects `the operation of the system of Figure 4 is the sameas that of Figure 3 above described.

Referring now to Figure 5 it will be seen that a number of successiveblock sections CI, C2, C3, C4 are indicated as adapted to be suppliedwith signaling -current from alternating current supply conductors 25extending along the track, track transformers TI, T2 etc. being providedfor each block section, the secondary windings of these transformersbeing connected to the track rails I, 2 as shown. Each block section isalso provided with its respective alternating current track relay TR2,TR3 etc., each of these relays being of the two element type comprisinga track Winding 23 connected across the track rails I, 2

and a local winding 21 supplied at times with current from the lsupplyconductors 25. The block sections are also provided with their re-Spective feed relays FR2, FR3 etc., repeater feed relays RFRI, RFR2etc., forthe corresponding feed relays FR2, FR3 etc.; detector relaysDR2, DRS etc., repeater detector relays RDR3, RDR4 etc., for thedetector relays DR3, DRfl etc.; and signal control relays SR2, SR3 etc.

Each block section is'also provided with its respective signal SI, S2etc., at the entrance end of each section and the various relays abovereferred to with the exception of the track relays TR2, TR3 etc.,` arearranged to be supplied with unidirectional current from rectiiiers WI,YW2 etc., connected through transformers TWI, TWZ etc., to the supplyconductors 25, the operation of the system being as follows:

Under normal conditions assuming that the block sections CI, C2, C3, C4are all unoccupied the feed relays of the block sections are main- E,

tained energized, the circuit of the feed relay FR4 for instance beingcompleted from the positive output terminal of rectifier WI, wires 28and 29, front contact 30 of relay DB2, wire 3|, front contact 32 ofrelay DRS, wire 33, front contact 34 of relay FR4, wire 35, relay FRAand wires 33 and 3l to the negative output terminal of rectifier W3which is connected to the corresponding negative terminals of the'otherrectifiers W2, WI

of the system by a common wire 38. It will thus Each of the feed relaysFR2, FR3 etc., being in its energized position, the correspondingrepeater feed relay RFR2, RFR3 is also in its energized or non-feedposition, the circuit of the repeater feed relay RFR2 for instance beingcompleted from the positive terminal of rectier WI, wire 28, frontcontact 40 of relay FR2, wire 4I, relay RFR2, wire 42 and common wire 38to the negative terminal of rectier WI. The repeater relays RFRI, RFR2etc., being thus energized the circuit of the wires 43 leading from thesupply conductors 25 to the primary windings of the transformers TI, T2etc., is broken at the contacts 53 of the relays RFRI, RFR2 etc.

The feed relays FRI, FR2 etc.,beingin their energized or non-feedposition and the corresponding track relays TRI, TR2 etc., beingdeenergized, the feed and track relays of each block section are inagreement with each other as illustrated by the agreement circuit ofFig. l so that the corresponding detector relays DR2, DR3 etc., areenergized. In the case of block section C2 for instance it will be seenthat a circuit is completed from the positive terminal of rectifier WI,wire 28, front contact 46 of feed relay FR2, wire 44, back contact 45 oftrack relay TR2, wire 46, detector relay DR2 and wires 4l and 48 to thenegative terminal of rectifier WI.

The detector relay of each block section being energized thecorresponding repeater detector relay is also energized, a circuit beingcompleted in the case of the repeater detector relay RDR4 for instancefrom the positive terminal of rectier W3, wires 49 and 5B, front contact5I of detector relay DRI-l, wire 52, relay RDR4, common wire 38 to thenegative terminal of rectier W3.

Each of the signal control relays SR2, SRS is also energized, thecircuit for the relay SR3 for instance being completed from the positiveterminal of rectifier WI, through wires 23 and 29, front contact 3i) ofrelay DR2, wire 3l, relay SH3, wires 42 and 38 to the negative terminalof the rectifier WI.

Each of the signals SI, S2 etc. is arranged to be jointly controlled bythe signal control relay, and the track and repeater detector relays insuch a manner that under normal conditions with the signal controlrelays energized operating current is not supplied to the signals SI, S2etc. When, however, a train or vehicle enters a block section, forinstance the section C2, the consequent deenergization of the signalcontrol relay SRS causes operating current to be supplied to the signalS3 to cause this signal to give a stop, caution or proceed indication.The signal control relays SRI, SR2 etc., thus serve as approach signalrelays and prevent any signal indication from being given until actuallyrequired by a train approaching a block section.

The particular signal indication given under these conditions isdependent upon the traffic conditions in a block section and in theblock section ahead. In the case of a train entering the block sectionCI for instance the feed relays FR2 and FR3 will both be operated totheir feed positions as will be hereinafter described. If now anothertrain or vehicle is occupying the block section C2 the track relay TR2will be deenergized by the presence of the train or vehicle and therelay TR2 is arranged when deenergized to control a signal operatingcircuit for a stop indication at the signal S2.

Ii, however, the block section C2 is unoccupied but another train orvehicle is present in block section C3, the track relay TR2 will beenergized but thedetector relay DRS will be deenergized owing to therelays TR3 and FR3 being in disagreement with each other. The repeaterdetector relay RDR3 will also be deenergized and the energized trackrelay TR2 and the deenergized yrepeater relay RDR3 jointly control asignal operating circuit for a caution indication at the signal S2.

In the event of both the block sections C2 vand C3 being unoccupied thetrack relay TR2 and the repeater relay RDR3 will be energized and underthese conditions these relays will control an operating circuit for aproceed indication at the signal S2. v

Referring now to the supply of signaling current to the track rails I, 2of the block sections in advance as a train or vehicle passes along thetrack, let it be assumed that the train or vehicle is occupying sectionCI and proceeding towards section C2.

The feed relay FR2 of section C2 has been deenergized by the action ofthe train entering the section immediately'in advance of the blocksection CI (which entry caused the associated DR relay to release) sothat the energizing circuit for the repeater feed relay RFR2 is broken'at the relay Contact 4I) of relay FR2. A circuit for the track rails ofblock section C2 from the supply wires 25 to the primary winding of thetransformer T2 is thus completed at the back contact 53 of relay RFR2.

At the moment when relay FR2 became released and before relay TR2 closedits front contact 45, relay DR2 was momentarily without energy. Due tothe slow releasing characteristic of relay DR2, however, this relayremains in its picked up position until an agreement circuit is againestablished over back contact 4I! of relay FR2 and front contact 45 ofrelay TR2. During the time that rthetrain remains in section CI, relayTR2 remains picked up since both of its windings 26 and 21 remainenergized. Consequently, relay TR2 does not release until the trainenters section C2.

The detector relay DRI (not shown) is deenergized because the entry ofthe train into section CI caused the associated track relay TRI (notshown) to become deenergized, thus establishing a disagreement betweenrelays TRI and FRI (not shown) which disagreement results in theinterruption of the circuit for relay DRI in the same manner that adisagreement between relay FR2 and TR2, for example, results in aninterruption of the circuit for relay DR2. The release of relay DRIinterrupts the circuit of the relay FR3 through wire 55, front contact56 of energized relay DR2 and wire 51 so that relay FR3 is deenergized.The corresponding repeater relay RFR3 is also deenergized by theinterruption of its circuit at front contact 58 of relay FR3. Relay RFR3closes its back contact 59 and completes a circuit from'the supply wires25 to the primary winding of the feed transformer T3.

Let it be assumed that with sections C2 and C3 unoccupied, a trainenters section CI. Relay FR2 will have been released due to the entry ofthe train into the section preceding section CI, and relay FR3 will nowrelease because the energizing circuit for this relay will be opened atthe front contact of the detector relay (not shown) associated withsection CI even though contact 56 of relay DR2 remains closed. Therepeater relays RFR2 and RFR3 will also be deenergized as a result ofthe released condition of relays FR2 and FR3. Track circuit current wasapplied to section C2 when relay FB2 released, over theback contact 59of relay RFRZ, and current is now also supplied to section C3 over theVback contact 59 of relay RFR3.

As a result, track relay TR3 becomes energized because its winding 26 isenergized from the track and its local circuit is closedat contact 39.Track relay TR2 remains energized, having been picked up in the samemanner as relay TRl (not sho-wn) when the train entered the sectionpreceding section Cl. Since there is now a new condition of agreementbetween the feed relay FR3 and the associated track relay TR3, thedetector relay DR3 which was momentarily deenergized during the transferinterval of relays FR3 and TR3 becomes re-energized without releasingits con tacts and maintains the detector repeater relay RDR3 in itspicked up condition, thus avoiding a flash of signal S2. Approach relaySR2A .is released because of the released condition of the detectorrelay (not shown) associated with section Cl. With relay SR2 deenergizedand re lays TR2 and RDR3 both energized, an obvious energizing circuitis closed for the proceed or topmost unit of signal S2.

When the train enters section C2, the track relay TR2 releases andcloses the energizing circuit for the stop unit of signal S2. Theresulting disagreement between relays FR2 and TR2 causes relay DR2V torelease, which releases, in turn, relay RDR2 (not shown), thus preparingan energizing circuit for the caution unit of the entering signal forsection CI. This caution signal will not be displayed, of course, unlessa following train isv approaching section Cl, and not until the trainfully clears the section Cl.

The entry of the train into section C2; also causes the release of feedrelay FRll, due to the opening of contact 30 of relay DR2. Current is,therefore, supplied to the rails of section C4 so that relay ".[R4 picksup, its local circuit having been closed at back contact 39 of relayFR4. Accordingly, under the above condition, relays TR4, DR4, RDR4, andSR4 are all energized and relay FR4 is released. The same conditionsexist in section C3, except that relay SR3 is released, thus energizingthe proceed unit of signal S3.

When the train completely clears section C2, track relay TR2 picks upandl since relay FR2 is released, anA agreement circuit is establishedwhich causes relay DR2 to pick up. When relay DR2 picks up, it closesthe pickup circuit for relay FRZ which picks up, in turn, and remainsenergized thereafter over its own holding circuit. The pickup of relayFRZ opens the local circuit of relay TR2 at contact 39, releasing thetrack relay. Also, the closing of front contact 4U of relay, FR2energizes relay RFRZ which cuts olf theV rail,current for section C2 'atcontact 59. During the transfer interval when relay FR2 picks up andbefore relay TR2 becomes fully released, relay `DR2 is momentarily onopen circuit but does-not release because of its slow-actingcharacteristic. The apparatus for section C2 is now fully restored tothe condition illustrated in Fig.,5.

The pickup of relay SR2 overV front contact 56 of zrelayDR2 deenergizessignal S2 behind `the train, unless a following train has enteredsection CI or is approaching this section. The sequence of operationtaking place when the train enters section C3 and the following sectionswill be clear without added explanation.

Although the control circuits for signal S2 only are illustrated indetail in the drawings, the circults for' the remaining signals willbeobvious since these signals are controlled in a similar manner.

The manner in which the supply of signaling current to the track railsof each block section is cut olf as the train or vehicle proceeds alongthe track will now be described with reference to a train assumed to bepassing through block sec-` tion C3 and entering block section C4.

So long as the train is in block section C3 the feed relay FR3 and thetrack relay TR3 are deenergized so that the circuit of the detectorrelay DR3 is broken at the front contact 58 of relay FR3 and relay DR3accordingly remains deenergized. Relay FR3 was, of course, deenergizedwhen the train entered section Ci and this relay will remain in itsdeenergized condition until such time as relay DR3 closes a'pickupcircuit for relay FR3 at front contact 64. This will not occur, however,until the train fully clears section C3 because it is only then thattrack relay 'IRB will pick up, establishing a condition of agreementbetween relays FR3 and TR3 which results in the pickup of relay DR3.

The block sections Cl and C2 being assumed to be unoccupied the detectorrelay DR2 and the corresponding relay DRI (not shown) of the sectionClare both energized.

As soon as the train has passed out of block section C3 the track relayTR3 is reenergized and closes its front contact 6I. A circuit is thuscompleted from the positive terminal of rectifier W2, wire t2, backcontact 58 of relay FR3, wire 63, front contact 6| of relay TR3, relayDR3 and wire 42 to the negative terminal of rectifier W2.

The relay DR3 is thus energized and closes its front contact 64, therebycompleting an energizing circuit for the relay FR3 from Wire 55, frontcontact 56 of relay DR2, wires 51 and 65, front contact 64 of relay DR3,wires 85 and 61, relay FR3 to wire 42 and common wire 38. The relay FR3is thus energized and effects the energization of the repeater relayRFR3 through a circuit including front contact 58 of relay FR3 and wire68' and the circuit of the primary winding of the4 feed transformer T3is thus broken at the front contact 59 of the relay RFR3 thereby cuttingoff the supply of signaling current to the track rails of block sectionC3.

The energization of the relay FR3 temporarily interrupts the circuit ofthe relay DR3 until the track relay when deenergized closes its backcontact 6I but the energizing circuit of the relay FR3 is maintainedthrough the front contact 69 of the relay FR3.

It will thus be seen that theA feed relay FR3 is energized and assumesits non-feed position as soon as the train has passed completely out ofthe corresponding block section C3v assuming that a following train isnot present in the block sections Cl or C2.

A similar action occurs as the train passes through each of the blocksections as will be readily understood.

As indicated in the figure the detector relays DR2 DR3 etc. and thesignal control relays SR2,

SR?, etc. are of the slow-acting type so as to en-v sure suitable delayin operation. This delay in the operation of the DR relay prevents anundesired release of this relay during the short time interval when,either upon the approach of a train or upon its exit from the section,there occurs a change from one agreement circuit to the other, forenergizing this relay. The slow release characteristic of the SR relaysprevents undesired signal flashes shoulda DR relay fail to bridge theopen circuit interval mentioned above.

Referring now to the modified system illustrated in Figure 6 theentrance of a train or vehicle into a block section is arranged toeffect '5 the supply of signaling current to one block section aheadonly and not to two block sections ahead as in Fig. 5, this supply beingmaintained until the train or vehicle has passed out of the section.

In the case of a train entering the block section C2 for instance thedetector relay DB2 is deenergized as in the system of Figure 5 owing tothe feed relay FR2 and the track relay TR2 of this section being bothdeenergized and therefore in disagreement. The energizing circuit ofrelay FR3 previously completed from wire 28 through wire 55, relaycontact 5S, wire 5l, relay Contact 69, wire 6l, relay FR3 to wire 42 isthus broken at the relay contact 56 and the relay FR3 is deenergized.The relay FR3 is thus in its feed position and the circuit of therepeater feed relay RFR3 is interrupted at the relay contact 58 of relayFR3. The relay RFR3 is consequently deenergized and closes its backContact, thereby effecting the supply of signaling current to the trackrails of block section C3 through the transformer T3.

Assuming that the block section C3 is unoccupied the track relay TR3 isenergized and the detector relay DRS is consequently maintainedenergized by way of back contact 58, wire 63 and front contact 6 I.

A stop signal indication is given at the signal S2 to a following trainentering the block section Cl as already described in connection withthe system of Figure 5 and when the train leaves block section C2 andenters block section C3 the relay DRS is deenergized and deenergizes therepeater relay RDR3. Since the relay DR2 is energized due to the exit ofthe train from section C2 a caution signal indication at the signal S2will be given to a following train while when the train leaves the blocksection C3 and enters the block section C4, the relay DRS is againenergized so that a proceed signal indication at the signal S2 is givento a following train in the block section Cl.

In both the systems of Figures 5 and 6 it will be understood that at aterminus the supply of signaling current to the first block section (notshown) of the system is effected by means of a pedal switch or itsequivalent which opens the holding circuit for the feed relay FR of suchrst block section in the manner previously eX- plained in connectionwith Fig. 3.

Although in the systems of Figures 2, 3, 4, 5 and 6 a detector relay isshown as provided for detecting agreement or disagreement between thetrack and feed relays of a block section it will be understood thatother equivalent arrangements for this purpose may be utilized, as forinstance by providing a switch device which is mechanically coupled withthe movable armatures of the track and feed relays .so as to make orbreak a circuit in accordance with the relative positions of thesearmatures.

The invention is evidently not limited to the particular systems andcircuit connections above described and illustrated which may be variedin many respects without exceeding the scope of the invention as definedin the appended claims.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

.75 1. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansfor at times supplying signaling current to the track rails of a blocksection, a relay connected across said track rails and responsive tosaid signaling current, and means controlled jointly by said supplymeans and by said relay for detecting the presence of a train in saidblock section.

2. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of a feedrelay for at times supplying signaling current to the track rails of ablock section, a track relay for said section responsive to saidsignaling current and having an energized and a deenergized position,and means dependent upon the position of said track relay and said feedrelay for detecting the presence of a train in said section.

3. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansoperated by a train approaching a block section for supplying signalingcurrent to the track rails of said block section, a track relay for saidsection having an energized and a deenergized position, and meansdependent upon the position of said relay and upon said supply means fordetecting the presence of a train in said section.

4. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansfor controlling the supply of signaling current to the track rails of ablock section, said means having a feed position in which current iscaused to be supplied to said track rails and a non-feed position inwhich the supply of current is cut oi, a track relay for said blocksection responsive to said signaling current and having an energized anda deenergized position, and means dependent upon the position of saidcontrol means and of said relay for detecting the presence of a train insaid section.

5. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansfor controlling the supply of signaling current to the track rails of ablock section, said means having a feed position in which current iscaused to be supplied to said track rails and a non-feed position inwhich the supply of current is cut off, a track relay for said blocksection responsive to said signaling current and having an energized anda deenergized position, and means dependent upon agreement between theposition of said control means and of said relay for detecting thepresence of a train in said section. g

6. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of asource of signaling current, a relay operated by a train approaching ablock section for controlling the supply of said current to the trackrails of the block section, a track relay for said block sectionresponsive to said signaling current, and means dependent upon both ofsaid relays for detecting the presence of a train in said section.

'7. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of asource of signaling current, a relay operated by a train approaching ablock section for controlling the supply of said current to the trackrails of the block section, a track relay for said block sectionresponsive to said signaling current, and means dependent uponcorrespondence 'between the noy sitions of said relays for detecting thepresence of a train in said section.

8. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of asource of signaling current, a relay for controlling the supply of saidcurrent to the track rails of a block section, a track relay for saidblock section, each of said relays having an energized and a deenergizedposition, a signal for said section, and means dependent uponcorrespondence between the positions of said relays for controlling theoperation of said signal.

9. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansdependent upon the presence of a train in a block section forcontrolling the supply of signaling current to a block section inadvance, a track relay for said advance block section, a signal for saidadvance block section, and means dependent upon said track relay andupon said control means for controlling the operation of said signal.

10. In a railway signaling systemthe combination with track circuitsconstituted by the track rails subdivided into block sections, of meanssection for controlling vthe supply of signaling current to a blocksection in advance, a trackl relay for said advance block sectionasignal for said advance block section, and means dependent upon trafcconditions in each of said block sections and upon the supply ofsignaling current to said sections for controlling the operation of saidsignal.

l1. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of meansfor effecting the supply of signaling current to the track rails of ablock section by the action of a train entering the preceding blocksection, means for cutting off said supply by the action of the trainleaving said block section, a track relay for said block section, asignal for said block section, and means controlled jointly by saidsupply means and by said relay for controlling the operation of saidsignal.

12. In a railway signaling system the combination withl track circuitsconstituted by the track rails subdivided into block sections, of a feedrelay for controlling the supply of signaling current to each of saidblock sections and having a feed position and a non-feed position, atrack relay for each of said sections having an energized and adeenergized position, a signal for each of said block sections, andmeans controlled in accordance with the corresponding positions of thefeed and track relays of each of a plurality of sections ahead forcontrolling the operation of the signal of a block section precedingsaid plurality of block sections.

13. In a, railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of a feedrelay for controlling the supply of signaling current to each of saidblock sections and having a feed position and a non-feed position, atrack relay for each of said block sections having an energized positionand a deenergized position, means dependent upon the entrance of a traininto a block section for causing the feed relays of a plurality of blocksections ahead to assume their feed positions, and means dependent uponthe corresponding positions of the feed and track relays in each of saidplurality of block sections for controlling the operation of the signalof a block section preceding said plurality of blocksections.

14. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of asignal for each of said block sections, a feed relay for each of saidblock sections having a feed position and a non-feed position, a trackrelay connected across the track rails of each of said block sectionsand having an energized and a deenergized position, a detectorvrelay foreach block section controlled by said feed relay and said track relayjointly and means controlled by said detector relay for controlling theoperation of said signal.

l5. In a railway signaling system the combination with track circuitsconstituted by the track rails subdivided into block sections, of asignal for each of said block sections, a feed relay for each of saidsections having a feed position and a non-feed position, a track relayconnected across the track rails of each of said block sections andhaving an energized and a deenergized position, a detector relay foreach block section controlled by said feed relay and said track relayjointly, and means including a detector relay for a given block sectionfor controlling the operation of the signal of said given section and oftheV signals of a plurality of block sections preceding said givensection.

GEORGES CAILLE.

